title: Decreased expression of type II protein kinase C in HL-60 variant cells resistant to induction of cell differentiation by phorbol diester.
abstract: To evaluate the molecular basis for susceptibility of the cell differentiation induced by 12-O-tetradecanoylphorbol-13-acetate (TPA), we examined biochemical activities and expression of subspecies of protein kinase C from HL-60 cells that are susceptible to differentiation induced by TPA and HL-60R cells, HL-60 variant cells that are resistant to such induction. Analysis of the subcellular distribution of protein kinase C revealed that the activity of this kinase in the cytosol from HL-60R cells was 30% of that from parental HL-60 cells but that the enzyme activities in the membrane showed similar values in these cells. Treatment of HL-60 cells with 100 nM TPA for 30 min resulted in a 75% decrease in protein kinase C activity in the cytosol and a 300% increase in this activity in the membrane. A minor subcellular redistribution of the enzyme activity was found in HL-60R cells after TPA treatment. Based on analysis of protein kinase C isozymes by hydroxyapatite column chromatography, the relative activities of types I, II, and III in the cytosol of HL-60 cells were 11, 80, and 9%, whereas those in HL-60R cells were 27, 36, and 37%, respectively. Type II isozyme was a major protein kinase C in the cytosol of HL-60 cells, but type II was less in the HL-60R cells. Among the three isozymes, type II enzyme was most sensitive to TPA with histone H1 as the substrate, although all three isozymes were activated Ca2+-dependently in the presence of phosphatidylserine. We suggest that the acquired resistance of HL-60R cells toward induction of cell differentiation by TPA may be associated with a decrease in the expression of the type II isozyme of protein kinase C.
authors.affiliation: Department of Internal Medicine, Mie University School of Medicine, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Nishikawa
authors.forename: F
authors.initials: F
authors.lastname: Komada
authors.forename: Y
authors.initials: Y
authors.lastname: Uemura
authors.forename: H
authors.initials: H
authors.lastname: Hidaka
authors.forename: S
authors.initials: S
authors.lastname: Shirakawa
mesh_terms: D015153:Blotting, Western; D002118:Calcium / Q000494:pharmacology; D002451:Cell Compartmentation; D002454:Cell Differentiation; D004075:Diglycerides / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D015470:Leukemia, Myeloid, Acute / Q000201:enzymology* / Q000473:pathology; D011493:Protein Kinase C / Q000378:metabolism*; D013347:Subcellular Fractions / Q000201:enzymology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
chemical_list: D004075:Diglycerides; D007527:Isoenzymes; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium; C013965:diolein